A vaccine reaction in your puppy is a type of allergic reaction when the body reacts—or more accurately over-reacts—to what should be an innocuous treatment. Reactions can be mild and last a short time but can sometimes cause long-term health problems or even become life-threatening.
They may happen only once or recur after every vaccination. Since vaccinations are supposed to prevent disease and rabies is required by law, a vaccination reaction requires careful management by both pet parents and the veterinarian.
Killed vaccines such as rabies and some injectable bacterial vaccines may be more likely to cause an allergic reaction than the modified live vaccines. That’s because of the amount of the disease material they contain and because of the adjuvants, substances designed to help stimulate an immune response.
What’s the Risk?
The group at the biggest risk for vaccine reactions is small neutered males less than 11 pounds and younger than one year who receive multiple vaccines in a single visit.
Opinions differ, and it’s not so much the breed as the size of the dog. The one thing everyone agrees on is the dogs that seem to be most at risk are young male neutered dogs weighing less than 11 pounds.
Why Some React and Others Don’t
The vaccine manufacturers say that according to their testing, it is okay to vaccinate as early as three months. The vaccine manufacturers and many guidelines say that the rabies vaccine should not be given before 12 weeks.
However—and this is a biggie—there can be conflicts between guidelines because they are based on scientific knowledge and thinking today, but the data used reflects the knowledge when the vaccine was licensed, which may be decades earlier. Everyone seems to agree on Type I and Type II reactions, but there is conflict as to what is classified as a reaction.
Reactions are due to the overall health of the dog, any breed sensitivity to the vaccine, the vaccine’s administration, whether the maternal immunity is still present, and other factors.
Type I Reactions
A Type I reaction is anaphylaxis and possible death. Anaphylaxis is an extreme allergic reaction (which affects many body systems) to a foreign substance which can range from a vaccine to food to mold to an insect bite and many more allergens. You can see symptoms almost immediately, but they can occur several hours later. Initial symptoms include:
- Puffy face
- Swollen eyelids, lips, and/or ears
Then they progress to:
- Cold legs
- Elevated heart rate
- Hyper excitement or depression
- Pale gums
- Shallow, rapid and difficult breathing
Type II Reactions
Type II reaction includes these reactions immediately following vaccination, and they are less severe than a Type I:
- Bleeding at the injection site
- Eye discharge
- Lump at the injection site
- Puppies that don’t like to be touched
- Puppies with no appetite
- Slight depression
- Sneezing and nasal discharge
- Swelling of the face
Timing of Vaccine Reactions
Most reactions occur within 48 hours of your dog being vaccinated, but some take longer. If your dog has a mild reaction, it generally will last a short time, just a few days. However, there is a huge controversy in the veterinary community about other side effects that can develop later in your dog’s life.
Many veterinarians say that most vaccinosis cases are mild and that the adverse reactions will be over within at least a few weeks. The World Small Animal Veterinary Association (WSAVA) says that most veterinarians or owners only consider the adverse reactions that happen within the first few hours to a day after inoculation to be associated with the vaccination. This organization cautions that many vaccine-caused reactions are not recognized as such, even when they occur shortly after vaccination.
Further, the WSAVA says, “Certain adverse vaccination reactions are not observed until days, weeks or even months and years after vaccination or revaccination. The autoimmune disorders and the injection site sarcomas, which are among the rare vaccine adverse reactions, may not develop for years after being triggered by vaccines.”
While there is controversy over what constitutes a vaccination reaction, it’s important to learn to recognize the possible signs and know what to do.
Vaccine Adverse Reactions. American Animal Hospital Association, 2020